KAJ LARSEN, CNN PRESENTS CORRESPONDENT: Four of the victims were found in a burlap-type material.

ANNOUNCER: Kaj Larsen traces the trail of a serial killer still on the loose.

LARSEN (on camera): This is Babylon, Long Island. It's an hour's drive away from Manhattan and it's known for beautiful million-dollar homes and secluded beaches. But that same isolation that people come here to seek, as of late, has been masking a darker element.

(Voice-over): In December, police in Long Island make a shocking discovery.

RICHARD DORMER, SUFFOLK COUNTY POLICE COMMISSIONER: I don't think it's a coincidence that four bodies ended up in this area.

LARSEN: For the past couple of years, women kept disappearing on Long Island. Now police think they may know why.

DORMER: Well, we could have a serial killer.

COHEN: We are dealing with a psychotic murderer.

LARSEN: Police still don't have answers, so we tried to get to the bottom of this eerie mystery.

GUS COLETTI, LONG ISLAND RESIDENT: That'd be the house. That's where it all began.

LARSEN: He tells me about a night last may that brought an unbelievable mystery to his doorstep.

COLETTI: She showed up at my door. And she was banging on the door screaming, "Help me, help me, help me." And I opened the door and she stepped in. She just stood there yelling, help me.

LARSEN: He later learned the woman was 23-year-old Shannon Gilbert.

COLETTI: I picked the phone up and start to 911 and she bolted out the door. And there was the car was coming down this road, slow, stopping, then go and stopping. And I asked him what he was doing. And he said, they had a party at Brewer's house, she got upset and left. And he was looking to find her to bring her back to the party, and he took off after her.

LARSEN (on camera): In the car?

COLETTI: In the car. And that was the last time I saw her.

LARSEN (voice-over): Coletti says he waited about 45 minutes for the police. By the time they arrived, Shannon Gilbert had vanished. When police came back later, they questioned the driver who took off after her. The driver told them that he brought Shannon from the city out to Long Island.

Police also questioned the man who, according to the driver, was throwing the party that Shannon left. That man was Joseph Brewer who did not return our phone calls to speak with us about this story.

Police told Coletti Gilbert wasn't just a party guest at Brewer's house.

COLETTI: Brewer was the one that hired this young lady to come out here.

LARSEN: Shanna Gilbert was an escort who posted ads on Craigslist. Because of her work as an escort, Shannon's sisters Sarah and Sheri often worried about her.

(On camera): Why did you guys come all the way down here?

SHERI, SHANNON GILBERT'S SISTER: Because my sister disappeared.

LARSEN: And when did you first know that your sister had gone missing?

SHERI: We first found out that Sunday. Her boyfriend called me and said that she hadn't come home in two days.

LARSEN: Did you have any thoughts then?

SARAH, SHANNON GILBERT'S SISTER: Honestly, yes, I just thought maybe she went off and found some friends, partied for two days and then she was going to come home. But then when we looked at her Sprint account and we figured if her friend called 911, that kind of changed our whole perspective of, you know, what might became of her.

LARSEN (voice-over): Shannon's phone records show she was on the phone with police for 23 long minutes before she showed up at Coletti's door for help.

DOTTIE LASTER, PRIVATE INVESTIGATOR: They didn't feel that they were being taken seriously or helped. And they were very distraught.

LARSEN: Gilbert's family started working with Dottie Laster (ph) and a team of private investigators to help find Shannon. Laster and her team had been digging into the case for months. They're especially concerned about that 911 call.

LASTER: She was in danger. She has not come back. She has not called anyone.

LARSEN (on camera): So what did you do?

SARAH: We pretty much from there tried to do our little own investigation, we made up flyers, passed them out, went door to door, and making up notes to give to (INAUDIBLE). I actually found a piece of her jewelry.

LARSEN (voice-over): In searching near Brewer's house they say they turned up something police had overlooked.

LASTER: The police had been there and searched it before the sisters went there but when the sisters went they said they found her earring on the front porch. So now they're more frantic, now they're more frustrated.

LARSEN: They got even more frustrated when they were left without suspects. Police ruled Brewer and the driver out as suspect, so the family began working with investigators to piece together any clues from her life before she disappeared.

SARAH: This is actually Shannon's signature.

LARSEN: We went back to visit Shannon's sister Sarah in the economically depressed region of Upstate New York where they grew up. Her sister says right before she disappeared Shannon was trying to get out of escort work.

SARAH: She was taking online classes and trying to stay away. But it's hard. We all grew up below poverty, you know?

LARSEN (on camera): She liked to dress up, she liked to have a good time, right?

SARAH: Yes.

LARSEN: She liked to party.

SARAH: Yes.

LARSEN: Was she like that in high school here?

SARAH: No, she was very quiet. She was like the bookworm.

LARSEN: This is Shannon Gilbert's middle school. She stared in the eighth grade production of "Annie" here. And like so many small town girls she had dreams of bright lights and big cities. But what she found was that the reality when she got there is it wasn't nearly as glamorous as she envisioned.

(Voice-over): When she couldn't pay the rent, she found work with an escort agency. Easy money paid the bills but ultimately made her life harder. After only a short time as an escort her family says she had an arrest record and a drug habit.

(On camera): I watched and you guys were very close. Were you close with Shannon like that as well?

SHERI: Yes. If one of us were missing I'm sure my sister now would do the same thing what we're doing to try to, you know, find her.

LASTER: The family kept urging the police search to please take the dogs. And it was about to get cold.

LARSEN (voice-over): When police finally took search dogs out to look for Shannon Gilbert months after she disappeared, they made a shocking discovery.

UNIDENTIFIED MALE: Missing Persons Unit called us out on Saturday to follow up on an investigation on a missing person. I saw the skeletal remains of a body.

LARSEN: Over the next couple of days, police would find three more sets of remains.

Coming up, the search for Shannon and the chilling possibility that a serial killer is on the loose.

(COMMERCIAL BREAK)

LARSEN: This past December, police out searching for Shannon Gilbert in the area where she disappeared in Long Island stumble on not one, but four badly decomposed bodies. DORMER: OK, good morning, everybody.

DORMER: I don't think it's a coincidence that four bodies ended up in this area. We could have a serial killer.

LARSEN (on camera): Four of the victims were found in a burlap-like material. That indicates two things. One, that it's very likely that those four victims were killed by the same person, a serial killer. And the second thing it suggests is that the killer most likely killed his victims elsewhere and transported them here to be dumped.

(Voice-over): In January, police put names to the remains. Shannon's family is relieved. She's not one of them. But they're still alarmed. All four victims are eerily similar to Shannon in age, height and looks, and every single one advertised on Craigslist as escorts.

Had police searched far enough? One of the bodies police identified was Amber Lynn Costello. Her sister, Kim Overstreet, is looking for answers.

KIM OVERSTREET, VICTIM'S SISTER: I was doing my own research and then trying to backtrack, getting everything I could. And you know it got to the point where I was obsessed with it.

LARSEN: Overstreet says police have told her very little about the investigation, so like the Gilbert family, she started doing her own digging.

OVERSTREET: It's my baby sister. You know? It (INAUDIBLE) every --

LARSEN: Kim herself used to work for an escort agency. She tried to teach her sister how to stay safe on the job.

OVERSTREET: I worked for (INAUDIBLE). And the guy had a (INAUDIBLE) in his name, but in his name (INAUDIBLE).

LARSEN: But she says her sister was a drug addict which made her even more vulnerable.

(On camera): So where we going now?

OVERSTREET: We're going to go to where Amber was staying, where the last place she walked out of was, where she met the guy who picked her up.

LARSEN (voice-over): This is the house where Amber was last seen. On the night that Amber disappeared, Kim was out of the state.

(On camera): Are you OK?

OVERSTREET: Yes. It's just that --

LARSEN: Tell me what's going on.

OVERSTREET: It's just this is the last place she was. You know? And I've been here so many times with her. And I just can't believe the one time I'm not with her it happened.

That morning she had got a call from a guy who was willing to set up a call for later that night. He called her again, maybe 10 or 5 a little after, and said that he was coming down the road, for her to go ahead and walk out.

She hung the phone up, gave the phone to the people that she was with and said if my sister calls, tell her I love her. She walked out the door, and was never seen again.

LARSEN (voice-over): Families and friends of the other victims tell similar stories. Each apparently disappeared after meeting clients.

Melissa Bartholomew's family may have even gotten a call from the killer. Just days after she went missing, Melissa's baby sister picked up the call because she thought it was her sister.

LYNN, VICTIM'S MOTHER: At that point it was five days when the first call came in and, you know, the caller ID Melissa, and she answers, she's all excited. And there's a guy on the other end.

LARSEN: The family got six separate calls from someone using Melissa's phone. Police don't want the details out there, but Melissa's mother Lynn will say the caller was threatening and wouldn't answer the family's questions.

LYNN: We didn't know what he did to her, if she was still alive, he wouldn't say, you know, if he wanted money or --

LARSEN: On that final call, Lynn says he confessed.

LYNN: He did confirm that he killed her. So that's why we were thinking this guy obviously held these girls and tortured them. Because why else would he have called for over a month unless he was just torturing us?

LARSEN: The family attorney Steve Cohen.

COHEN: That's how we know that we're dealing with a monster, a Hannibal Lecter, someone who's very bright and very calculating and very patient.

LARSEN: In April, police find the remains of up to six more victims. They speculate about something truly horrifying. There may be more than one serial killer at work here.

DORMER: Certainly the medical examiner is going to be looking at the possibility that Shannon Gilbert is one of the remains.

LOU COLOMBO, RETIRED LONG ISLAND POLICE OFFICER: There is no secret that we've been dumping bodies out here for decades.

LARSEN: Lou Colombo is a retired officer from Long Island. He shows us how hard it is to search here.

COLOMBO: You can just take a look at it and know that you literally cannot walk in from the roadway into this area. You know, and as a result, it lends itself to discarding a body, making it almost impossible to find.

LARSEN: He says police have always known the area as a good place to get rid of a body and he explains why this will be a tough case to crack.

(On camera): In all fairness to Nassau County, to Suffolk County Police Departments, there aren't really hard and fast clues here, right?

COLOMBO: Nothing. There's no physical evidence of forensics unlike you would find in a conventional crime scene, in an apartment or a home.

LARSEN (voice-over): Shannon Gilbert was not among the remains police found. It's been over a year since she disappeared. As the families of the victims gather to remember their loved ones, none are any closer to knowing what happened.

SARAH: We're hopeful because she wasn't recovered so that does give us a hope that she still might be out there. But at the same time it is just -- you know, we want that closure, we want to know.

COHEN: We are dealing with a psychotic murderer who is very bright, very deliberate, very calm, very well prepared, who will kill again.

ANNOUNCER: Next on CNN PRESENTS.

POPPY HARLOW, CNN PRESENTS CORRESPONDENT: Was the bullying part of the reason you think, Erica, that your best friend killed herself?

UNIDENTIFIED MALE: We have no evidence that bullying or harassment took place in any of those cases.

ANNOUNCER: And later, what it takes to fight the multi-billion dollar illegal animal trade. A monkey refuge where the people live in cages and animals roam free.

(COMMERCIAL BREAK)

MICHELLE JOHNSON, SAMANTHA JOHNSON' MOTHER: This is Samantha's swimsuit. And it's been hanging here and I just can't put it away.

HARLOW (voice-over): A swimsuit hanging lifeless since November 2009 when Michelle Johnson' only daughter took her own life.

JOHNSON: To see your child lay there lifeless and not know why. HARLOW: What she would learn is that her 13-year-old's world had become unbearable.

JOHNSON: We believe that she was just hiding from everybody because she was feeling helpless. Samantha was kind of a tomboy and she was perceived as gay.

HARLOW (on camera): Was she gay?

JOHNSON: No. We don't think she was gay. She was 13.

HARLOW (voice-over): Samantha was the first of seven students to commit suicide in a single Minnesota school district in less than two years. Parents and friends tell us four of those teens were either gay, perceived to be gay, or questioning their sexuality, and at least two of them were bullied over it.

(On camera): We're about 30 minutes outside of Minneapolis, in Anoka- Hennepin. This is the biggest school district in the entire state. But the reason we're here is because it has become a battleground over homosexuality in the classroom.

(Voice-over): The district has a controversial curriculum policy that says staff must remain neutral on matters of sexual orientation. It's ignited a culture war. One that's playing out in school board meetings.

UNIDENTIFIED FEMALE: The homosexual lifestyle is a social controversial issue that should be addressed in the homes and not the schools.

UNIDENTIFIED FEMALE: These children are human beings. We're allowing these kids to be treated as second-class citizens.

HARLOW: Allegations of bullying have brought unwanted media attention and CNN has learned a federal investigation to this quiet suburban community.

MIKE THURSTON, STUDENT: A student threw me up against a wall, lockers, and screamed "fag" at me.

HARLOW: Mike Thurston, an eighth-grader at Anoka Middle School, isn't gay but he's the president of his school's gay-straight alliance.

THURSTON: A student, for whatever reason, came up to me during social studies said to me, so how big was it in your mouth last night?

HARLOW: The bullying made school a daily battle for kids like Mike and Samantha. Erica Hoops was Samantha's best friend.

HOOPS: She didn't feel safe anywhere. During volleyball they would call her names like fag, and be like go over to the boy's locker room. You shouldn't be in here.

HARLOW (on camera): Did any adults see this? HOOPS: Yes. But they didn't ever do anything. I was in the locker room at one point when she was getting harassed and the coach was looking at it first. But she didn't stop it anyway.

HARLOW (voice-over): Samantha's mother, Michelle, didn't learn about the bullying until she showed up one day at volleyball practice.

JOHNSON: And the coach said, can I help you? And I said I'm Samantha Johnson' mother. And where is she? And she said, oh, I haven't seen Samantha in weeks. And I thought, what? How can that be? She's taking the late bus home. So she said, well, I know that there is a couple of girls that are being very mean to her.

HARLOW (on camera): So the coach knew she was being bullied.

JOHNSON: Right.

HARLOW: Had she ever you told that before you came down to practice?

JOHNSON: No.

HARLOW: Did you see anyone bullying Samantha?

(Voice-over): The district requires staff to report all bullying. We reached out to Samantha's coach.

UNIDENTIFIED FEMALE: There was issues everywhere in her life and her situation, and they were addressed to the best of the ability and I just -- I don't have anything else to say.

HARLOW: Samantha never made it to another volleyball practice. Just like Justin Aaberg didn't make it to his 16th birthday. Justin was gay.

BRANDI, JUSTIN AABERG'S FRIEND: And this one girl told the whole school --

HARLOW: His friend Brandi says the bullying began shortly after Justin was outed in the eighth grade.

BRANDI: He told me that somebody had, like, grabbed his balls and said, "You like that." And (INAUDIBLE) counselor knew that something was wrong and she ran up behind.

HARLOW: Justin's mother, Tammy Aaberg, said she was never contacted about the incident. And then just months before taking his life --

TAMMY AABERG, JUSTIN'S MOTHER: He came to me and said, mom, a kid at school says I was going to go to hell because I'm gay.

HARLOW (on camera): Can you say without a doubt that Justin's suicide was connected to the bullying?

AABERG: Yes, I believe it was connected. Do I know what the last thing was that happened that made him -- made the final act? No, I don't know what it was. HARLOW (voice-over): We will never know what drove Samantha and Justin to take their lives.

But here's what we do know. In a school newsletter, and in a voice mail to staff, Superintendent Dennis Carlson denies any connection between bullying and the suicides.

DENNIS CARLSON, ANOKA-HENNEPIN SUPERINTENDENT: Based on all of the information we've been able to gather, none of the suicides were connected to incidents of bullying or harassment.

HARLOW: A statement that angered family and friends.

HOOPS: I just kept thinking, you liar, liar, liar, because there's totally a connection.

HARLOW (on camera): Was the bullying part of the reason, you think, Erica, that your best friend killed herself?

HOOPS: Most definitely, there's no question about it.

HARLOW: Did the school district talk to you after Samantha committed suicide?

HOOPS: I never went and got talked to.

JOHNSON: What bothered me most is nobody asked us.

CARLSON: We have dozens of people looking into each one of though suicides. They talked to as many people as they can surrounding that suicide.

HARLOW (voice-over): We asked Superintendent Carlson why no one talked to Samantha's mother or her best friend.

CARLSON: We did not do a formal investigation. We would only do a formal investigation if there was some indication that there was need for there.

HARLOW: Why wouldn't there be a need any sort of that when you have kids killing themselves?

CARLSON: There needs to be some evidence that bullying, harassment, was a part of their life in that school. I cannot emphasize enough, kids need to come forward to the adults in the building and say, "We're being bullied." If they do not, there isn't much we can do.

JOHNSON: I am the mother of Samantha Johnson who was a student at Fred Moore.

HARLOW (voice-over): After his public statement Michelle e-mailed the superintendent saying she had talked to the volleyball coach, the vice principal and the counselor about Samantha's bullying. Carlson insists the district followed up with those staff members but could not release the records citing privacy concerns. He says Michelle now refuses to speak with them.

JOHNSON: I can't trust the school when Samantha was alive, then I don't know why I can trust them now.

HARLOW: When we come back, one teacher who wants to take on the district.

(On camera): Are you afraid that you could lose your job just being here talking about this?

JEFFERSON FIETEK, TEACHER: Realistically? Yes.

(COMMERCIAL BREAK)

HARLOW (voice-over): It's 9:00 on a typical school night.

FIETEK: I just got a text from a young lady.

HARLOW: An Anoka middle school teacher Jefferson Fietek is in crisis mode.

FIETEK: It looks like she's got a friend who's in crisis and thinking about suicide.

HARLOW (on camera): Just now.

FIETEK: Just now. Yes.

HARLOW: How often does this happen?

FIETEK: It's about once a week? Sometimes more.

HARLOW (voice-over): It turns out to be just one scare of many.

FIETEK: This is where I had another kid hospitalized. Last week I had another kid hospitalized.

HARLOW (on camera): For what?

FIETEK: For getting so overwhelmed that suicide seems the only way out.

HARLOW (voice-over): Fietek is openly gay and he's the advisor for his school's gay-straight alliance. He says suicidal feelings are common among gay youth and those questioning their sexuality.

(On camera): In fact, studies since the 1990s consistency show gay and lesbian youth have suicide attempt rates at least twice that of their heterosexual peers. Fietek's school district, Anoka-Hennepin, has been hard-hit. The question is, what role does school climate really play?

(Voice-over): This is the only Minnesota school district we could find with a curriculum policy that bars teachers from taking a position on homosexuality and says such matters are best addressed outside of school. It's become known as the neutrality policy and some teachers say it's part of the problem.

JERI SCHULTZ, ANOKA-HENNEPIN TEACHER: Because there's so much we can't do and say to help create a more accepting and affirming and welcoming environment that would eliminate some of that bullying in the first place.

FIETEK: It is a censorship policy. It is censorship. There's nothing neutral about taking the side of the oppressor.

HARLOW (on camera): It seems like you're saying this is contributing to leading these kids to the brink.

FIETEK: It is contributing to creating a hostile, toxic environment.

HARLOW (voice-over): But Superintendent Dennis Carlson says the district has a comprehensive bullying policy and has piloted a bullying tip line. He has the neutrality policy is a reasonable response to a divided community.

CARLSON: It is a diverse community and what I try to do as superintendent is walk down the middle of the road.

UNIDENTIFIED MALE: Sir -- sir, you're out of line. You're out of line.

UNIDENTIFIED MALE: You're out of line, too, sir.

MELISSA THOMPSON, ANOKA-HENNEPIN PARENT: I mean this idea of check your identity at the door, would you tolerate that? We are not advocating that we teach homosexuality, that we teach anything other than tolerance.

SCHUE: They don't need to be promoting a particular point of view on that. Parents have a right to raise their children the way they want to and the school district doesn't need to be sitting there telling kids your parents are wrong.

HARLOW (on camera): And I know you're in support of the sexual orientation policy and I'm just hoping you'll tell me why.

(Voice-over): Some local conservative parents have banded together forming the Parents Action League. We tried multiple times to talk to them.

HARLOW (voice-over): On their Web site they push for parents' rights and for schools to focus on core academics. In a recent letter to the local newspaper, one active community member wrote, "It is irresponsible for educators to promote the "It's OK to be gay" message to students when homosexuality is such a high-risk behavior.

Now the fight has gone federal. CNN has confirmed the Departments of Justice and Education are investigating the district. After receiving a complaint regarding allegations of harassment and discrimination based on sex.

MARY BAUER, LEGAL DIRECTOR, SOUTHERN POVERTY LAW CENTER: This policy sends kids the message that who they are is not OK.

HARLOW: An advocacy group, the Southern Poverty Law Center, and the National Center for Lesbian Rights have filed a lawsuit challenging the neutrality policy. The SPLC was present for CNN interviews involving its clients.

In response to the lawsuit, the district says they are confident that they are complying with the law and that the policies, practices and procedures in place ensure the safety of students.

The district also says it takes, quote, "strong exception" to the outrageous media statements the district is not concerned about the safety of its students. And it has asked the advocacy groups to help train its staff in supporting gay students.

But Superintendent Carlson stands by the neutrality policy. Still, he knows there's a problem.

CARLSON: We need students to speak up and say, "I am being bullied." We know that gay students in our district on a daily basis struggle with bullying and harassment.

HARLOW: If you doubt that, just listen to these kids from Anoka Middle School's gay-straight alliance. Many aren't gay.

UNIDENTIFIED MALE: It says gays in the name of the club, it's like, you're automatically that, and not everyone who goes there is so.

HARLOW: But just being in the club can make them a target.

(On camera): Raise your hand if you've been bullied in the last month. Last week? What about today? How does hearing these words, you're gay, you're a fag, you're different -- how does this make you guys feel?

UNIDENTIFIED MALE: Like, picks at you every day. It's like, gets a little bit deeper and deeper and deeper. It's like a wound that won't heal.

HARLOW: Why did you decide to join the gay-straight alliance?

UNIDENTIFIED MALE: It's just a safe place to be where no one will judge you for who you are.

HARLOW (voice-over): The battle over the neutrality policy is the adult's fight. The kids just want to be safe and they don't want anymore of their friends like Samantha Johnson to die.

UNIDENTIFIED MALE: She was sick of everything. And miss her grandpa.

HARLOW: Sick of what?

UNIDENTIFIED MALE: The bullying.

ANNOUNCER: Coming up, the hazards of preserving life in the wild.

(COMMERCIAL BREAK)

LYON (voice-over): The illegal wildlife trade is a $10 billion a year business. Wild animals torn from nature, killed for food, or captured live, confined, chained, sold as exotic pets.

I wanted to know what happens when you rip an animal out of paradise and turn it into a play thing, and what it takes to put things right.

(On camera): Hey, what's going on here?

(Voice-over): So we headed out "Into the Wild."

To truly appreciate why wild animals belong in the wilderness, we have to go there. So we went to one of the most diverse ecosystems in the world, the Costa Rican rainforest.

(On camera): And we're flying down here to this remote area. This is known as the Peninsula de Osa.

(Voice-over): We left the big city heading for the crown jewel of Costa Rica's park system.

(On camera): We're here in the center of Puerto Jimenez. This is a small little gold mining town. It's also the gateway into the Corcovado National Park. In order to get in there you've got to hike for a couple days or you can do what we're doing and we're taking the arrow taxi.

This is the shortest landing strip in all of Costa Rica. They literally clear-cut the rainforest. If we don't make it, the plane goes into the ocean. We've got life vest in the back of the plane.

(Voice-over): We packed up all of our gear and our guide into a tiny single engine plane and held on tight.

(On camera): We're flying over entry of Corcovado.

(Voice-over): Corcovado is one of the most biologically intense places on earth.

(On camera): That had to be the coolest landing.

(Voice-over): Home to the largest and only primary low-land rainforest in the world, 140 different animal species, many endangered.

Professor Eduardo Carrillo of the National University of Costa Rica is a top expert in jungle ecology and he's one hell of a guide.

(On camera): And he says that an awful lot just passed through this trail.

(Voice-over): In just 24 hours, we saw more than most park visitors see in a week. Rugged, remote, stunningly beautiful inside the forest and out.

(On camera): So this is Rio Sirena. This river meets the ocean right here and during high tide, which is right now, bull sharks sometimes up to 12 feet long come through here and feed. And there's also crocodiles. Swimming through the waters just across this area would be risking your life.

Eduardo is fighting this fighter monkey right up in this tree.

Why do you shake the leaves?

PROF. EDUARDO CARRILLO, BIOLOGIST: Because I have to challenge them and they're going to come and fight with me?

LYON: Really? Whoa. He just (INAUDIBLE) this and threw it out to us. Mean little guy.

CARRILLO: Yes.

LYON: Why would he throw a stick at us?

CARRILLO: He smells healthy.

LYON: We're standing right in the middle of a pack of peccaries. These are the main food source for pumas, jaguars and all the cats here in the forest. And people living nearby the forest come in and hunt these because they taste really good.

So we're heading into the jungle now. Obviously the sun's down and at night, a whole different slew of creatures comes out. We're just about 20-feet away from this giant puma.

CARRILLO: We can get a little bit closer to the puma.

LYON: Can I get closer?

CARRILLO: It's fine. (INAUDIBLE) would be close. We can get (INAUDIBLE).

LYON: It's incredible to be this close to such a magnificent animal in the wild.

CARRILLO: Beautiful. She looks really well conditioned.

(CROSSTALK)

LYON: She's getting up. She's getting up. What does that mean?

CARRILLO: Nothing.

LYON: Is she coming towards us?

CARRILLO: Don't go anywhere. OK? Beautiful. Don't worry. Even for me, it is not so often to see something like that.

LYON: And you've been doing this for 20 years.

CARRILLO: Yes. An amazing experience.

LYON: Definitely an adrenalin rush. How does it make you feel when you see people that have animals that you find in the rainforest as pets?

CARRILLO: That is a big problem. It's really nice to have babies but when they go, they become wild. They have instincts. They can bite people. It's the same with other animals. A wild animal is a wild animal always. They are not (INAUDIBLE). You can feel -- beautiful sunset with the forest. I feel that leer. Can you feel it? We are not alone in this life. We are not the only species.

LYON (voice-over): It's beautiful and it's isolated. To wildlife traffickers, this beauty equals profit. But as we're about to see, help is just a boat ride away.

CAROL CREWS, SANTUARIO SILVESTRE: I'm a certified jungle woman.

LYON (on camera): You're the woman of the jungle, huh?

(Voice-over): She has a single mission -- rescue and return the animals to the wild whatever the cost.

(On camera): Oh, yes, she's got bite marks all over here. You've got the scars to prove what you do.

CREWS: These are the badges of courage I wear.

LYON (voice-over): And by the end of our journey, we had badges, too.

(On camera): What do you call these? Monkey tattoos?

CREWS: This is a sanctuary tattoo.

LYON: Sanctuary tattoo.

(COMMERCIAL BREAK)

LYON (voice-over): As dawn breaks over Puerto Jimenez, Costa Rica, a small town on the West Coast, you can hear the eerie sound of a passing troupe of howler monkeys. Animal traffickers take anything from macaws to monkeys, from the rainforests of Central America, and sell them to the highest bidder at dozens of auctions held across the United States.

They often become victims of abuse and neglect. Caged, chained, tranquilized, or sometimes beaten into submission.

CREWS: I'm a certified jungle woman.

LYON: Those who are lucky enough to be rescued are given to Carol Crews.

(On camera): She's got bite marks all over here. You've got the scars to prove what you do.

CREWS: These are the badges of courage I wear.

LYON: Do visitors ever get trounced on by monkeys?

CREWS: On occasion if they don't do as I tell them to do. Yes, they do.

LYON (voice-over): Fifteen years ago, Crews sold everything she had, packed her bags and left San Francisco and moved to Costa Rica. Crews runs the Sanctuario Silvestre. It's is a wildlife rescue center that borders a national park.

What makes her rescue center unique, it's the only one I've ever seen where the people live in cages and animals roam free but freedom means my crew and I are at the mercy of the monkeys.

Meet Sweetie. When she was just 4 days old, poachers shot her mother for her meat, ripping Sweetie off her dead mother's back, throwing her into the forest leaving her to die. And because of her past, Sweetie is not so sweet. Crews says she especially dislikes men.

CREWS: She definitely rules.

LYON (on camera): Every time we enter the kitchen we have to run.

So humans live in cages (INAUDIBLE) to eat lunch. And while she runs free.

CREWS: This is where I do all of my work. Home sweet home.

LYON: All the monkeys sleep --

CREWS: Right next to mama.

LYON: Yes?

CREWS: Life is good in the cage.

LYON: Why did you decide on that philosophy for you and your volunteers to be living in cages and the animals to be roaming free? CREWS: I think we're working with an incredibly intelligent species here. Primates. And if you acclimate them to life in a cage, I don't think they're as apt to leave. They're not as courageous. They have to break that bond of what have they've lived in for three to four years.

Little one over here was confiscated from a hotel from tourists. Came to us almost half dead. It was so dehydrated.

LYON: Hey, little guy. Hello. Oh, he's kissing me. These guys are small but they're some of the loudest mammals on earth. When you hear them in the forest, it is so creepy.

(Voice-over): All kinds of creatures live here. Most of all, Carol's favorite, monkeys. These Capuchins (ph) have to be caged because of their aggression.

CREWS: They are true victims with the pet trade. I will enter this cage only with the idea that I'm the sacrificial lamb.

LYON: Carol tells us she can't go into the cage because she's the alpha monkey in this jungle and the Capuchin would try to knock her off. They're considered the third smartest land mammal on earth. We went into the cage so that makes us the fourth.

(On camera): These are very aggressive monkeys. They're constantly moving around which is one of the reasons they shouldn't be kept as pets.

OK, what's going on here?

UNIDENTIFIED MALE: I don't know. I'm getting out of here.

LYON: The last guy that came through here had to get 13 stitches. They're called a sanctuary tattoo.

(Voice-over): Remember Sweetie? She's the spider monkey with a grudge against men. One day she'll leave the sanctuary and join a wild troupe, but today we get a first-hand look at how quickly a tame monkey can get dangerous.

CREWS: Walk away. Walk away.

LYON (on camera): See. She doesn't hate men. Producer Steve was holding one of the spider monkeys and he slipped and she got scared and bit him on the head. And so now he's got --

CREWS: This is a sanctuary tattoo.

LYON: Sanctuary tattoo. This kind of show why, you know, people think they think they can just keep these monkeys as pets.

CREWS: It is wildlife.

LYON: And this would happen. She wasn't even trying to -- CREWS: Why do you think it's called wildlife? I've been bitten by almost every species here at the sanctuary. And it just -- you know, it just goes with the job.

Look, she got a leaf. What a good monkey. He's still a little sad. He hasn't quite gotten over the loss of his mother yet.

LYON: Are these like your adopted children?

CREWS: Yes, they are. And it is a bittersweet moment when they leave but if you ever witness releasing an animal back to the wild, it is such a euphoric feeling that it gives you the energy and the strength through all those losses, through all that heartache to continue because it is such an incredibly good feeling.

When Lulu, our 3-year-old howler monkey, gave birth, baby was still wet and she brought him down for me to see. And that just about took me to my knees.

LYON (voice-over): Bittersweet is a good word to describe what Carol Crews does. She helps the animals she cares for so much will leave her. But she knows because of the damage people do to animals, there will unfortunately always be more.

ANNOUNCER: On the next CNN PRESENTS, we'll take you where most people never go, exposing polygamy's dirty secrets.

UNIDENTIFIED MALE: We're dealing with the exploitation of children. Of young girls, for sexual purposes.

ANNOUNCER: Plus, a once-top secret military program --

UNIDENTIFIED REPORTER: But you know, I was scared on purpose right in the face. Just got me again.

ANNOUNCER: Enlisting animals to protect the country. Next Sunday night on CNN PRESENTS.